1. Field of the Invention
The present invention pertains to devices for deflating vehicle tires in response to movement of the vehicle. More particularly, the present invention pertains to an antitheft device which automatically releases air from the tires of a vehicle when the vehicle is stolen or driven by an unauthorized operator.
2. Description of the Prior Art
Due to the increasing number of auto thefts, a number of antitheft devices have been developed. Many of these devices attempt to provide some foolproof method of locking the doors of the vehicle or of preventing ignition of the enging. However, most of these devices are fairly easily overcome, particularly to the sophisticated auto thief.
In U.S. Pat. No. 3,003,539, a device is disclosed which may be locked on the tire of a vehicle and is specifically designed to deflate the tire in case the vehicle is stolen. The deflating mechanism includes a plunger having a spring which biases the plunger toward engagement with the tire valve. The mechanism is set by disposing a portion of a pivoted lever between the deflating plunger and the tire valve. A weight is attached to the end of the lever. If the weight is not locked in place and the automobile begins to move, centrifugal force will cause the weight to pivot the lever out of engagement with the end of the tire-deflating plunger, allowing it to engage the tire valve and releasing air from the tire. While this device appears to be workable, it is relatively bulky and the lever which actuates the device is subject to tampering. For these and possibly other reasons, this device has not found commercial acceptance.
There are other devices in the prior art for releasing air from vehicle tires. However, most of these do not appear to be concerned with theft of the vehicle. For example, U.S. Pat. Nos. 3,532,140 and 3,838,717 disclose relatively complicated devices used to simulate tire blowouts for testing of vehicles. These are devices which operate on pressure and have mechanisms to quickly release air from a tire to simulate a blowout.
U.S. Pat. Nos. 2,470,873 and 2,737,223 disclose apparatus which allows an airplane tire to be inflated to a relatively high take-off pressure but after take-off, releases some of the air so that upon landing, the tire will not be as likely to blow out. In neither one of these devices is all the air allowed to completely escape the tire.